A wide range of rock types can be found along the trail ranging from Lias and Upper Greensand to the much younger chalk.
The majority of the trail from Ashmore to Beaminster follows a chalk ridge formed around 100 million years ago in warm shallow seas. Beyond Beaminster the underlying geology changes to greensand capped hills lying above older rocks from the Jurassic created much earlier between 200 and 150 million years ago.
The chalk escarpment which the trail follows runs across one third of the county and extends as far as Swanage. Chalk is composed from countless billions of microscopic plants that died and then been compressed over time.
The chalk is very thick and the chalk ridge itself is a remnant of a vast plateau of chalk which was pushed upwards between southern England and northern France. The action of water such as rivers and springs has eroded the chalk to create the river valleys but much stranger to explain are the steep sided dry valleys. These formed during the last Ice age when the ground was frozen. When the snow and ice melted, great floods poured down the valleys, eroding the frozen chalk. Today the valleys are dry as any rainwater simple soaks into the chalk. The edges of the great chalk plateau are marked by steep slopes that offer views across a completely different landscape composed of clay vales and sand stone hill tops.
This geology supports many different habitats and has shaped how the land has been farmed and the settlements which have emerged along the trail. The trail passes through a number of intimate and varied landscapes on its journey to the sea. There are steep grassland fields and areas of scrub and woodland, while the fertile coombes and flatter, clay vales like the Blackmore Vale have been ploughed to produce crops. The Marshwood Vale to the south west of Beaminster has remained relatively unchanged over the last century. This is made up of a patchwork of small irregular shaped fields, copses, thick ancient hedgerows and marshy ground.
Over 40% of the county of Dorset, including the trail, falls within an Area of Outstanding Natural Beauty. This national designation recognises the importance of the landscape and helps to protect and enhance this unique and beautiful landscape now and for future generations.
Dorset Area of Outstanding Natural Beauty.
Cranborne Chase
Cranborne Chase is previously a Medieval royal hunting ground covering an area of over 250,000 acres (101,250 hectares) between the Rivers Stour, Nadder, Allen and Crane, this area of high rolling downland and woodland is now protected as an Area of Outstanding Natural Beauty.
Wide-ranging views
All along this ridge top trail there are breathtaking and far reaching views. These include magnificent views spreading out across the Blackmore Vale as far as Stourhead, King Alfred's Tower, Shaftesbury, Duncliffe Hill, Fontmell Down and Win Green in Wiltshire. On a clear day you can sometimes see the outline of the Quantocks and Exmoor hills in the far distance and southwards along the English Channel to the Isle of Wight. Further westwards along the trail you get stunning views across Dorset, Somerset and Devon. These include the Marshwood Vale, Golden Cap and the sea to the south. Eastwards is Chesil Bank stretching along the coast and Hardy's Monument and Rampisham masts in the distance with Dartmoor, Exmoor and the Quantocks to the west and northwards the Polden and Mendip Hills.